Answer:
2.895*10^24
Explanation:
mass of Oxygen give = 153.9g
molar mass of O2 molecule = 16*2=32g/mol
n= mole
To find the mole
n= mass/ molar mass
n= 153.9/32
n=4.81mol.
To find the number of molecules of o
Nm= number of molecule
Nn = Number of mole
NA = number of Avogados
Nm= Nn * NA
Nm= 4.81 *6.02*10^23
Nm= 2.895*10^24

How can telescopes aid visualizing the electromagnetic spectrum?what is the “best place” for telescopes “to detect most radiation” and why?

Astronomers use telescopes that detect different parts of the electromagnetic spectrum. Each type of telescope can only detect one part of the electromagnetic spectrum. There are radio telescopes, infrared telescopes, optical (visible light) telescopes and so on.
The best place to detect most radiation is above the blocking atmosphere, so some telescopes are put in orbit around the Earth. Even visible light is distorted by the atmosphere, so clearer pictures can be got from orbiting telescopes.